[Three_thirty_I]

Since out cars don't have (well the E90 330i doesn't) temperature gauges I have always used my oil level indicator as a guide to know when the engine is up to temperature, and since it generally takes a fair bit longer than my E46 I am pretty sure that it has always been a safe method. But as such, I am perfectly familiar with it since I use it every time I drive the car. And it always shows the level that the oil level sensor has settled on, never fluctuates...

So yesterday I drove the car and to my surprise noticed that the oil level was showing as 50% when the previous time that I drove the car and since the oil was changed earlier this year it was always on 100%. If it was to drop it should have been 75% if anything, not 50%, unless it was all of sudden using or leaking oil which is clearly isn't. I let the car stand for a bit and went for a drive a bit later on, and still shows 50% which just doesn't make sense.

I then took the car for a drive later last night and gave the engine some WOT and high revs at freeway speeds - all of a sudden the level shows 100% again, and it stayed like this for a while. But I gather with the high revs and coincidentally the mileage since the oil change the level then dropped to 75% and has stayed there - today as well.

But does this mean that the sensor is on the way out, or could it have been some moisture in the oil that may have confused it? Point is, it has never done this before, and it of course really had me concerned and annoyed.

Really hoping someone has some advice or past experience with this...

[e90pilot]

I think BMW has a funny algorithm for that sensor. I've noticed anomalies with mine as well. I know it does measure resistance as a means of measuring quantity and temperature does change resistance. That's one of the reasons the quantity will not display until the oil warms up. I think your sensor is fine.

My sensor was leaking a bit so I replaced it. Turned out to be a huge mistake! My oil pan was warped where the oil level sensor sat so when I put a new one in, the gasket didn't seal properly and it leaked EVERYWHERE. It made a mess of my garage and driveway. I had to get a new oil pan which was really expensive.

[Three_thirty_I]

I hear what you are saying and I did read another thread here where a member went into some detail about how this sensor works, but no explanation as to why the level would fluctuate like this.

Now also as I said above, in the more than 3 years that I have had this car and considering that I check the oil level indicator every time I drive the car, I have never once had this happen! And my car has always used some oil between services, so when it drops it's always in 25% increments and for that matter never changes back to the previous value once it has dropped. When it dropped to 50% from 100% on Saturday, it stayed at this level when I drove it several times, but then when I took it for a drive that night and gave it some hard driving it suddenly shot up again to 100% - it then dropped down to 75% where it has stayed which I gather was just a coincidence in terms of how the engine generally uses oil.

My problem is that if it was doing this from the day I bought the car then that's fine, but it hasn't...

Originally Posted by e90pilot

I think BMW has a funny algorithm for that sensor. I've noticed anomalies with mine as well. I know it does measure resistance as a means of measuring quantity and temperature does change resistance. That's one of the reasons the quantity will not display until the oil warms up. I think your sensor is fine.

My sensor was leaking a bit so I replaced it. Turned out to be a huge mistake! My oil pan was warped where the oil level sensor sat so when I put a new one in, the gasket didn't seal properly and it leaked EVERYWHERE. It made a mess of my garage and driveway. I had to get a new oil pan which was really expensive.

[F32Fleet]

Probably moisture.

[Efthreeoh]

How many miles are on your car?

[Three_thirty_I]

Originally Posted by Socom

Probably moisture.

I suppose this is possible, the car had some shorter distance driving for a few weeks and then it went for a proper longer drive on a very warm day, so maybe there had been some moisture burn off and while the level was still showing as 100%, the next time (being Saturday) that I drove the car the sensor was acting up until later that night. Still very strange since this has never happened before and with the same conditions...

Originally Posted by Efthreeoh

How many miles are on your car?

The car currently has just short of 72k km on the clock, so low mileage for the age - things wear out differently, either from use, or simply age.

[Efthreeoh]

It's probabaly not the sensor. The behavior is strange sometimes

[Three_thirty_I]

Originally Posted by Efthreeoh

It's probabaly not the sensor. The behavior is strange sometimes

Well, keeping an eye on it, but so far it is staying on 75% which is fine. I am also wondering if the new software that I am running (literally a few weeks now) may have had anything to do with this, not sure...